Abstract
In this paper, the transient and steady-state performances of an isolated self-excited induction generator driven by a wind turbine and feeding power to a dynamic load such as a three-phase induction motor are analyzed. Mathematical modeling and simulation study of the whole system, including the wind turbine, induction generator, capacitor, pulse width modulated voltage source inverter, and dynamic load, are carried out with closed-loop voltage and frequency controller. The complete system is modeled in the stationary $d-q$ frame and validated by comparing simulation and experimental results at no-load. The same mathematical model is then used to study the transient performance of the self-excited induction generator supplying to a dynamic load. When the induction motor is connected to the induction generator without any voltage and frequency controller, it causes severe transients in electrical and mechanical variables of the generator. Due to the large starting-current requirement of the induction motor, there is a collapse of the terminal voltage of the generator. A bidirectional pulse width modulated source inverter with DC link battery is connected with the generator and operated in closed-loop control mode to maintain voltage and frequency and to operate the induction motor successfully with variable wind speed and mechanical load.
Highlights
Renewable energy sources, such as wind, photovoltaic, and hydropower plants are recently being paid much attention universally due to excess exploitation of fossil fuels and associated environment pollution
With a fixed capacitor bank connected across the stator terminals, it is not possible to keep the terminal voltage of the selfexcited induction generator (SEIG) constant under varying loads because of the variable reactive power demand, which is not met by the fixed capacitor bank
Taking these factors into account, this paper focuses on a simple and reliable voltage and frequency controller giving very less transient oscillation and very low total harmonic distortion (THD) values for a SEIG-fed induction motor load
Summary
Renewable energy sources, such as wind, photovoltaic, and hydropower plants are recently being paid much attention universally due to excess exploitation of fossil fuels and associated environment pollution. In [15], a simple scheme was reported with a pulse width modulated (PWM) voltage source inverter (VSI) by taking the R and R − L load only Taking these factors into account, this paper focuses on a simple and reliable voltage and frequency controller giving very less transient oscillation and very low THD values for a SEIG-fed induction motor load. With the designed control scheme, the VSI is taking care of the induction motor load and source perturbations by injecting the required amount of reactive or active power for maintaining the rated voltage and frequency of the SEIG. The wind turbine drives the SEIG at a desired speed and appropriate values of capacitor bank are connected across the stator terminals of the SEIG to initiate the self-excitation process and to generate the rated voltage at no-load. System modeling The whole system under study has the following components: wind turbine, induction generator, shunt excitation capacitor bank, induction motor load, and PWM VSI
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